Method and apparatus for absorbing the energy of bullet impacts

ABSTRACT

A method for and apparatus absorbing the energy of a projectile strike by a multiplicity of energy dissipating elements of high mass that are contained within a spaced defined by walls. A projectile passing through one of the walls transmits its energy to a multiplicity of energy dissipating elements, such as hardened steel balls or various shaped objects of high mass, by causing energy transfer and distribution through a loose mass of the energy dissipating elements and disintegrating the projectiles. Energy absorbing apparatus embodying this method may take the form of a static or moveable bullet or projectile trap, an energy absorbing external barrier or shelter on vehicles, and portable personnel protection structures for use in a tactical environment. The energy absorbing and dissipating elements are subject to some movement in response to the energy imparted by the projectiles and quickly settle after the energy has been dissipated.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a method and a wide variety of mechanical devices for absorbing and distributing energy, particularly the energy of projectiles such as bullets, artillery shells, shrapnel, and the energy that may be delivered to structures by blunt force impacts. More particularly, the present invention concerns a wide variety of specific energy absorbing apparatus, such as static or moveable bullet traps, protective walls of structures and protective energy absorbing and dissipating protective shields for vehicles, protective personnel enclosures, etc.

2. Description of the Prior Art:

A projectile trap, more specifically referred to as a bullet trap, is typically provided in the form of an earthen dike or berm that defines a rather abrupt shoulder or embankment. During firearm practice or matches bullets are fired through targets and become embedded within the earth of the dike or berm. Repeated bullet strikes in the earth of the abrupt shoulder or embankment of a dike or berm will result in damage which must be repaired from time to time. Moreover, the earth of the embankment of the dike or berm will accumulate a significant amount of bullet material, such as copper and lead, which may need to be removed from time to time, especially if the continued presence of these materials is objectionable as potentially harmful to the environment. Typically the soil containing the bullet residue will need to be dug out and separated from the soil. This is a very costly and time consuming process which is done only in the event that the soil must be returned as nearly to its original condition as is possible. And of course the bullet materials are lost during typical firing range activities even though these materials are valuable commodities that could be re-used. Therefore, it is desirable to provide a bullet trap system that sustains minimal damage during normal use and which can be easily and quickly repaired with minimal effort and cost. It is also desirable to provide a bullet trap system that enables a high percentage of the bullet materials to be recovered and re-used.

A bullet trap may also be composed of sand bags or bags of other materials, such as sawdust, wood shavings, or the like and can be composed of heavy wooden beams such as railroad cross-ties. However, during firearm shooting activities these materials typically become damaged in a relatively short period of time and must be repaired or replaced at considerable labor and significant expense. It is desirable to provide a bullet trap system that will remain functional for long periods of time and when repair of replacement becomes necessary, can be simply and efficiently repaired or replaced via the use of minimal labor and cost.

Vehicles, such as military trucks, armored personnel carriers and tanks are often provided with armor that renders them somewhat safe from penetration by the projectiles of rocket propelled grenades, bullets of heavy machine guns and light artillery rounds. There are times, during tactical situations, where additional protection is needed to enable such vehicles to absorb a significant amount of ordinance energy. Personnel may come under attack during a tactical situation and may need the protection of temporary energy absorbing shelters to enable them to remain securely protected for the duration of an attack. Therefore, it is desirable to provide an energy absorbing system that can be simply and efficiently used to provide an external barrier of energy absorbing protection as needed for the protection of personnel and equipment within a wide variety of vehicles. It is also desirable to provide an energy absorbing system that may be efficiently installed during field conditions that will enable the establishment of an energy absorbing structure to provide protection for personnel from the otherwise damaging effects of various types of projectiles.

SUMMARY OF THE INVENTION

It is a principal feature of the present invention to provide a novel energy absorbing system that enables the provision of various types of bullet traps, including static and moveable bullet traps.

It is another feature of the present invention to provide a novel energy absorbing system that is applicable to bullet traps and provides for the recovery of bullet materials, such as copper and lead, and enables a bullet trapping environment to be maintained essentially clean of bullet material accumulation.

It is also a feature of the present invention to provide a novel energy absorbing system that can be designed for the protection of various types of vehicles and can be quickly and easily attached to the vehicle structure to provide an additional outer layer or barrier which has the capability for absorbing a significant amount of the energy of projectiles that may strike the vehicle.

It is another feature of the present invention to provide a novel energy absorbing system that can be efficiently employed to erect a temporary protective barrier or enclosure that has the capability for absorbing and dissipating much of the energy of a projectile striking the barrier or enclosure and is capable of providing protection for personnel behind a protective barrier or within a protective enclosure.

Briefly, the various objects and features of the present invention are realized through the provision of an energy absorbing barrier or shelter having spaced walls and with the space between the walls being at least partially filled with a multiplicity of energy absorbing elements, such as hard and dense metal balls or other metal or non-metal objects, that can be moved in response to the application of the energy of a projectile strike. Movement of the energy absorbing and dissipating elements causes the transfer of force and energy dissipation to other surrounding energy absorbing elements. When the energy of a projectile strike has been absorbed and dissipated the energy absorbing elements will quickly settle by the action of gravity. The energy absorbing elements also cause a projectile, such as a bullet, to be disintegrated to a particulate form within the loose mass of energy absorbing and dissipating elements and to descend through the loose mass and fall from the bullet trap. The resulting bullet material particulate may then be collected and re-used.

The outermost one of the walls of the energy absorbing system is readily replaceable and is composed of a material that is relatively easy to be penetrated by a projectile and yet maintain sufficient structural integrity for effective retention of the energy absorbing elements. Such a wall structure may be composed of a tough, resilient and durable polymer material, such as polyethylene, for example. The outermost wall or front wall panel should have sufficient structural integrity and elastic memory to retain the moveable energy absorbing elements within the space between the walls and permit multiple projectiles to penetrate the wall panel material without impairing its structural integrity and with minimal resistance and to impact and impart energy to the energy absorbing elements. The energy that is imparted to one or more of the energy absorbing elements will move the energy absorbing elements against the resistance of the weight and mass of all or most of the other energy absorbing elements, thus distributing the energy of the projectile throughout the loose mass of energy absorbing elements that are present within the wall space. Movement of the energy absorbing elements will be minimal when impacted by a firearm projectile or other type of projectile, because the energy of the projectile will be efficiently transferred from element to element within the loose mass of energy absorbing elements and because the mass of the projectile will typically be much less than the combined mass of the energy absorbing elements.

The innermost wall of the energy absorbing system can be composed of a material that is quite resistant to penetration by the energy of a projectile and which provides an inner layer of protection which can be penetrated only by a direct strike of the projectile against the innermost wall, a condition that is not expected to occur. The innermost wall of the energy absorbing system can be composed of a panel or plate of a durable metal such as steel, particularly a hardened steel material having a thickness in the range of from ⅛″ to about ¾″.

The energy absorbing elements can be provided in a wide variety of geometric forms, such as spheres or balls, oval objects, triangular objects, square objects, etc., which can be placed in the space between the inner and outer walls as a random mass and which will be moveable as the energy of the projectile is distributed within the mass. The energy absorbing elements are composed of a metal having considerable mass, such as hardened steel, and will be resistant to excessive deformation by the energy of a projectile.

It has been determined through tests that hardened steel balls, such as concrete grinding balls, having a size in the range of about one inch in diameter serve quite well for energy absorption in a bullet trap that is impacted by bullets in the size range of up to .50 caliber. In this test case the outer or front wall of the bullet trap was composed of a polymer material such as polyethylene and the rear wall of the bullet trap was composed of a hardened steel plate having a thickness of about ⅜″. After having been impacted by the bullets of approximately 1,000 to 1,500 rounds of rifle ammunition having a size up to .50 caliber and with approximately 70% of the ammunition having a size of 0.762 mm, the polymer wall panel was replaced, though it still had the capability for retention of the hardened steel balls. The steel plate forming the innermost or rear wall of the bullet trap was essentially undamaged at this point.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features, advantages and objects of the present invention are attained and can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the preferred embodiment thereof which is illustrated in the appended drawings, which drawings are incorporated as a part hereof.

It is to be noted however, that the appended drawings illustrate only a typical embodiment of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.

In the Drawings:

FIG. 1 is an isometric illustration showing a bullet trap embodying the principles of the present invention;

FIG. 2 is a partial cross-sectional illustration taken along line 2-2 of FIG. 1 and showing spherical energy absorbing and transferring elements filling much of the space between the containment walls of the bullet trap of FIG. 1;

FIG. 3 is an enlarged cross-sectional illustration showing energy absorption and dissipation of the bullet trap embodiment by means of force vectors and movement arrows;

FIG. 4 is an elevation view of a moveable, i.e., rotatable bullet trap representing an alternative embodiment of the present invention;

FIG. 5 is an isometric illustration showing the rotatable bullet trap of FIG. 4 and showing bullet fragments being deposited for collection after having descended through the energy absorbing mass of balls or other energy absorbing and dissipating elements during rotation of the target support and bullet trap;

FIG. 6 is a section view of the rotatable bullet trap taken along line 6-6 of FIG. 5;

FIG. 7 is a section view showing in diagrammatic form an energy absorbing structure being mounted adjacent to the outer surface of a vehicle structure; and

FIG. 8 is a top plan view showing a portable personnel protection structure embodying the principles of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

Referring now to the drawings and first to FIG. 1, the method and apparatus for absorbing energy of the present invention may conveniently take the form of a bullet trap, which is shown generally at 10, and which has a front or outer wall panel 12 that is composed of a tough and durable polymer material, such as various forms of polyethylene, and which has sufficient structural integrity and elastic memory to provide for containment of a multiplicity of energy absorbing elements 14. The bullet trap 10 also includes a rear or inner wall panel 16 that is composed of a substantially rigid and durable plate of material, such as steel.

The front and rear wall panels are disposed in spaced relation, having a spacing from about 6 inches to about 12 inches and defining a space or compartment 18 which contains a multiplicity of the hard and dense energy absorbing elements 14 which may comprise hardened steel concrete grinding balls having a diameter of about one inch. These grinding balls are relatively inexpensive and are readily available since they are widely used for grinding concrete and rendering it to a state for re-use. Preferably, the energy absorbing elements 14 are deposited within the space or compartment 18 in the form of a loose mass of energy absorbing elements that are in contact with one another and some of the energy absorbing elements are in contact with the inner surfaces of the front and rear wall panels. The bullet trap also includes a top wall 19 side walls 20 and 22 and a bottom wall 24 that have sufficient structural integrity for containment of the heavy and dense energy absorbing elements. The bottom wall 24 and, if desired, the side walls as well define openings or perforations to permit bullet components to fall from the bullet trap structure, rather than accumulating in the lower part of the compartment 18. The energy absorbing elements 14 are essentially poured through an access opening 26 of the top wall into the space or compartment 18 and constitute a loose mass and are in contact with one another and are in contact with the bottom and side walls. Since the energy absorbing elements are not connected with one another they are free for movement relative to one another in response to the energy of a projectile strike. It is not necessary that the compartment 18 be completely filled with the energy absorbing elements 14, it being only necessary that the energy absorbing element have the capability for energy responsive movement as energy is imparted to the mass of energy absorbing elements, such as by the strike of a bullet or other type of projectile. A hinged closure 27 for the top opening 26 is provided with a locking mechanism 25 so that it can be secured in its closed condition.

For servicing of the bullet trap apparatus, the loose mass of energy absorbing elements can be poured from the compartment 18 by unlocking and opening the hinged closure 27 of the access opening 26 and by inverting the bullet trap. Alternatively, by releasing the front wall panel 12 from its support framework the hardened steel grinding balls 14 will be released and will descend from the compartment 18. The hardened steel grinding balls 14 or other energy absorbing elements can also be removed from the compartment 18 by cutting away a lower portion of the front wall panel 12 to make as large an exit opening as is needed for controlled exit and recovery of the energy absorbing elements. Typically, servicing of the bullet trap apparatus will be done when the front panel 12 has been damaged by bullet penetration to the point that it has become unserviceable and requires replacement. It is not necessary to discard the energy absorbing elements when replacing the front wall panel because they will have little or no deformation from being used many times. After a new front wall panel has been installed the energy absorbing elements will typically be poured back into the compartment 14.

The bullet trap structure is typically formed by a generally rectangular framework, shown generally at 30, having front and rear generally rectangular frames 32 and 34 that are each composed of vertical and horizontal structural members. The front and rear frames 32 and 34 are interconnected by side frame members 36 and 38. The side and bottom wall structures may be composed of any of a number or materials such as sheet metal, heavy duty wire, expanded metal, in fact any material that is capable of providing for secure containment of the energy absorbing elements 14 and having the durability and structural integrity to accommodate movement of the energy absorbing elements in response to the energy of a bullet strike. The front wall panel 12 and the rear wall panel 14 are fixed to the generally rectangular framework by means of bolts, screws or by any other suitable means for attachment.

The rear wall panel may be somewhat permanently secured to the rectangular framework, since it is quite durable and will seldom need replacement. However, the front wall panel 12, since it is penetrated by each bullet or projectile that strikes the bullet trap, will need replacement after having been penetrated by many hundreds of bullets. Consequently, the front wall panel is preferably removably secured to the rectangular framework 30, such as by means of screws or bolts so that its replacement can be accomplished quickly through the use of simple and readily available tools.

Referring to FIG. 3, the function of the front wall panel 12 and the energy absorbing elements 14 is shown diagrammatically and energy distribution within the loose mass of energy absorbing elements is indicated by force vector arrows. In this case the spherical energy absorbing elements are preferably composed of a hardened dense material such as steel and the front wall 12 is preferably composed of a polymer material such as polyethylene. As shown in FIG. 3, a bullet 39 will penetrate the front wall panel 12 and because of the resilience and structural integrity of the front wall panel material, due to the polymer chain characteristic and elastic memory of the polymer that develop during polymerization, will substantially close the path of bullet penetration so that the resulting path is much smaller than the diameter of the bullet. This feature enables many hundreds of bullets to pass through the polymer front wall panel and yet permits the front wall panel to maintain its retention characteristics so that the energy absorbing elements will not pass through the front wall panel and become lost. As a bullet enters the space or compartment 18 between the front and rear wall panels 12 and 16 it will strike one or more of the hard and dense energy absorbing elements and, due to the resistance offered by the mass of energy absorbing elements, will essentially become deformed and disintegrated such that its component materials will be rendered to particulate form. The disintegrated copper, lead and other component materials of multiple bullets will in time descend through the loose mass of energy absorbing elements and fall from the bottom of the bullet trap via the perforations. These materials may be collected and re-used if desired.

When one or more of the energy absorbing elements is impacted by a bullet or other type of projectile, the energy absorbing element that receives the energy of the impact will transfer a portions of the energy to adjacent energy absorbing elements with which it is in contact. This will typically result in some movement of the energy absorbing elements which have been subjected to bullet impact or have received energy from adjacent energy absorbing elements. The energy will be transferred in the form of force vectors as shown by the energy transfer arrows as illustrated diagrammatically in FIG. 3. Though for purposes of simplicity FIG. 3 shows the energy absorbing elements arranged in two dimensional manner, it should be borne in mind that the mass of energy absorbing elements is three dimensional, thus causing the force of the impact to be distributed throughout a portion of the loose mass of elements. The dimension of the mass of loose and quite dense energy absorbing elements 14 is sufficiently wide, between the front and rear containment wall panels 12 and 16, that the force of bullet impact, even when heavy .50 caliber bullets are used, will only minimally be received by the rear wall panel 16 and will have no tendency to penetrate the rear wall panel. Tests indicate that hardened steel concrete grinding balls having a one inch diameter function quite well as energy absorbing elements for a typical bullet trap embodying the principles of the present invention. These hardened grinding balls will typically be re-used for many cycles of bullet trap servicing or repair.

While the present invention is described herein particularly as it relates to static bullet traps, such as shown in FIGS. 1-3, it is not intended to limit the spirit and scope of this invention solely to this particular field, because this invention is readily applicable to a wide variety of apparatus and methods of use. For example, as shown in FIGS. 4 and 5, the apparatus may conveniently take the form of a moveable, i.e., rotatable, bullet trap that is designed for receiving and dissipating the energy of a multiplicity of strikes by a class on non-explosive projectiles including small arms bullets up to and including .50 caliber. Of late, a number of firearms have been developed for highly accurate ultra long-range shooting activity, particularly for use by sniper personnel in a tactical environment. It is appropriate, therefore, to provide training activities for this type of military and law enforcement personnel and for long range match shooting activity and to provide a bullet trap mechanism to accommodate the energy of the heavy bullets that are fired during training activities for long-range shooting with heavy caliber bullets.

A rotatable bullet trap device, shown generally at 40 in FIGS. 4 and 5 comprises a framework or support structure shown generally at 42, which is preferably of circular configuration as shown, but which may have other configurations, including square, octagonal, triangular, etc., without departing from the spirit and scope of the present invention. The framework 42 incorporates rear and front framework panel support structures 44 and 46, one or both of which are supported for rotation by an axis 48 which is in turn mounted to any suitable support structure 49. Rear and front wall panels 50 and 52 are mounted to the support framework structures 44 and 46 by bolts, screws or any other suitable mounting fasteners and are disposed in spaced relation, defining an energy dissipation and distribution compartment 54 therebetween.

The energy absorption and dissipation compartment 54 is defined in part by one or more peripheral containment walls 56 that are mounted to the rear and front wall support framework structures 44 and 46 and serve to provide for containment of a multiplicity of energy absorption and dissipation elements 58. The energy absorption and dissipation elements 58 are composed of a hard and dense material such as steel. It has been determined, as mentioned above, that hardened steel concrete grinding balls having a size in the range of about 1″ are relatively inexpensive, readily available, and serve quite well for resisting damage by firearm projectiles and dissipating the energy of firearm projectile strikes. However, the energy absorption and dissipation elements may take many other forms within the spirit and scope of the present invention and may be composed of other hard, dense and durable materials as desired.

The rear wall panel 50 is preferably composed of a hard and dense plate of material such as steel, and has a thickness in the range of from about ⅛″ to about ¾″. The thickness of the rear wall panel 50 is sufficient to resist penetration by any bullets or other projectiles that pass through the front wall panel 52 and enter the energy dissipation and distribution compartment 54. Since the front wall panel is intended to be penetrated by the projectiles, it is mounted to the front framework structure 46 in a manner that promotes simple and quick replacement. The front wall panel is preferably composed of a tough, pliable and durable material such as polyethylene or any other suitable polymer material. It is necessary that the tough and durable polymer material have an elastic memory, made possible by its long chain polymer characteristics, so that holes or paths that are formed in the front wall panel by projectile passage will be substantially closed by the elastic memory of the material. This feature enables the energy absorption and dissipation elements to be efficiently retained within the compartment 54 even when the front panel has been penetrated by many hundreds or thousands of firearm projectiles. However, when replacement of the front wall panel becomes necessary, it may be replaced in a short period of time through the use of simple and readily available tools.

During use of the bullet trap apparatus of FIGS. 4-6, bullets readily penetrate the front wall panel 52, enter the energy absorption and dissipation compartment 54 and strike one or more of the energy absorption and dissipation elements 58. The resistance provided by the hard and dense characteristics of the energy absorption and dissipation elements causes a bullet to essentially disintegrate and form particulate of its component materials, such as copper, lead and any other bullet constituents. This bullet particulate will work its way through the interstices of the loose mass of hardened steel spheres or other configurations of the energy absorption and dissipation elements, so that it descends by the force of gravity to the bottom portion of the bullet trap. Rotation of the bullet trap, which is afforded by the rotary mounting system of FIGS. 5 and 6, causes agitation of the energy absorption and dissipation elements and tends to accelerate separation of the bullet particulate or debris from the loose mass of energy absorption and dissipation elements. The peripheral containment walls 56 define a multiplicity of perforations 60 that are of sufficient dimension to permit most of the bullet debris to exit the compartment 54 and descend by gravity to a collection container 62. Periodically, the bullet fragment contents of the collection container can be emptied into a salvage container so the bullet fragments can be re-used or safely discarded as desired.

With reference to FIG. 7, it is intended that the method and apparatus of the present invention be applicable for providing an external layer of protection for vehicles, such as trucks, tanks, armored personnel carriers and the like. A vehicle “V”, having an external wall 63 having an outer wall surface 64, can be provided with an external energy absorption and dissipation system having an inner or rear wall panel 66 and a front or outer wall panel 68 that are mounted in spaced relation and define an energy absorption and distribution compartment 70 between the walls. The inner or rear wall panel 66 is composed of a hard and durable dense material such as steel and the front or outer wall panel 68 is composed of a material that can be penetrated by the non-explosive projectiles of small arms fire. A multiplicity of hard and dense energy absorption and distribution elements 72 are located in the compartment 70 in the form of a loose mass. The hard and dense energy absorption and distribution elements 72 will absorb and dissipate the energy of the projectiles, tending to cause disintegration of the projectiles, thereby providing protection for the occupants of the vehicle. Removable energy absorbing blocks or sections may simply be assembled to or removed from the outer surfaces of the vehicle according to the needs of the environment in which the vehicle is being operated.

As an alternative to the method and apparatus that is described above in connection with FIG. 7 the outer wall surface 64 of the vehicle may constitute the rear or inner wall of the compartment 70. In this case the front or outer wall panel 68 will be mounted in spaced relation with respect to the outer wall surface 64 of the vehicle. The energy absorbing and distributing elements within the compartment 70 will be disposed in engagement with the outer wall surface of the vehicle.

As shown in FIG. 8, the energy absorbing and dissipating principles of the present invention are also adaptable for use in a tactical environment for the protection of military or law enforcement personnel. When military personnel are in a tactical field environment, and have no other suitable cover against the harmful effects of hostile small arms fire, a portable personnel protection structure, shown generally at 80 may be rapidly set up. A portable inner or rear wall assembly 82 and a portable outer or front wall assembly 84 may be installed in spaced relation, defining an energy absorption and dissipation compartment 86 between them. The rear or inner wall assembly will be composed of a hard and essentially rigid plate material, such as steel, while the front or outer wall panel assembly can be composed of a polymer or other suitable material that will permit the projectiles of small arms fire to enter the compartment and cause the energy of small arms projectiles to be absorbed and dissipated by the energy absorbing and dissipating elements that are located within the compartment.

If desired, the inner and outer wall assemblies may be supported by a simple portable foundation and may have a simple and portable wall cap that helps to maintain proper spacing between the inner and outer wall assemblies. A multiplicity of energy absorbing and distributing elements 88 are placed in the compartment 86 so as to substantially fill the compartment space. The energy absorbing and distributing elements are of similar composition and function as described above. When the protective enclosure is no longer needed at a particular site, it may be simply and quickly disassembled, transported to a different site and installed as needed. The protective enclosure may also be used to provide for protection of personnel from the damaging effect of wind propelled debris, hail and the like in the event storms are encountered during field conditions.

In view of the foregoing it is evident that the present invention is one well adapted to attain all of the objects and features hereinabove set forth, together with other objects and features which are inherent in the apparatus disclosed herein.

As will be readily apparent to those skilled in the art, the present invention may easily be produced in other specific forms without departing from its spirit or essential characteristics. The present embodiment is, therefore, to be considered as merely illustrative and not restrictive, the scope of the invention being indicated by the claims rather than the foregoing description, and all changes which come within the meaning and range of equivalence of the claims are therefore intended to be embraced therein. 

1. A projectile energy absorbing and dissipating device for absorbing and dissipating the energy of a class of projectiles, comprising: a support structure; a rear wall being mounted to said support structure and being resistant to penetration by the class of projectiles; a front wall being mounted in spaced relation with said rear wall and defining a compartment therewith, said front wall being readily penetrable by the class of projectiles; containment walls defining closures for said compartment; and a multiplicity of energy absorbing elements being arranged in loose and moveable relation within said compartment and being disposed in engagement with adjacent energy absorbing elements and being contained by said front, rear and containment walls.
 2. The projectile energy absorbing and dissipating device of claim 1, comprising: said support structure being a support framework; said rear wall and said front wall being mounted to said support framework and being secured in spaced relation; and said containment walls being mounted to said support framework and being cooperative with said rear and front walls for ensuring against displacement of said energy absorbing elements from said compartment.
 3. The projectile energy absorbing and dissipating device of claim 1, comprising: said projectile energy absorbing and dissipating device being a bullet trap for the class of projectiles including small arms projectiles up to 50 caliber; said rear wall being composed of a hard and dense material of sufficient thickness to resist being penetrated by the class of projectiles; and said front wall being composed of a material that is penetrable by the class of projectiles and which ensures minimal damage to said front wall by projectiles passing through it.
 4. The projectile energy absorbing and dissipating device of claim 1, comprising: said rear wall being defined by a panel composed of steel; and said front wall being defined by a panel composed of a polymer material.
 5. The projectile energy absorbing and dissipating device of claim 3, comprising: said containment walls being composed of a material of sufficient structural integrity for containment of energy absorbing and dissipating elements composed of dense hard material and being sufficiently perforate to permit projectile component residue to pass therethrough and be deposited for collection.
 6. The projectile energy absorbing and dissipating device of claim 1 being in the form of an exterior protective device for vehicles, comprising: said rear wall being mounted externally of a vehicle structure.
 7. The projectile energy absorbing and dissipating device of claim 1 being in the form of an exterior protective device for vehicles, comprising: said rear wall being defined by an external surface of a vehicle and constituting said support structure.
 8. The projectile energy absorbing and dissipating device of claim 1, wherein said device is in the form of a rotatable bullet trap, said device comprising: said support structure being mounted for rotation; said containment walls defining perforations of sufficient dimension to permit projectile component debris to pass therethrough and to prevent said energy absorbing elements from passing therethrough; and during rotation of said device projectile component debris descending through said multiplicity of energy absorbing elements, passing through said perforations of said containment walls and being deposited for collection.
 9. The projectile energy absorbing and dissipating device of claim 1, wherein said device is in the form of a protective enclosure for personnel, said device comprising: said rear wall being defined by rear wall panels arranged at a site to form an inner enclosure wall structure having an opening for personnel entrance and exit; said front wall being defined by front wall panels disposed in spaced relation with said rear wall panels and arranged to form an outer enclosure wall structure and to define said compartment; and said The projectile energy absorbing and dissipating device of claim 1 poured into said compartment and defining a mass of loose energy absorbing elements.
 10. The projectile energy absorbing and dissipating device of claim 9, comprising: said rear wall and said front wall being of portable nature and being recoverable for use at a different site when use of said protective enclosure is no longer needed at the site; and said multiplicity of projectile energy absorbing and dissipating elements being recoverable for use at a different site.
 11. A projectile energy absorbing and dissipating device for absorbing and dissipating the energy of a designated class of non-explosive firearm projectiles including small arms projectiles up to 50 caliber, comprising: a support framework structure; a rear wall being panel being mounted to said support framework structure and being resistant to penetration by the class of firearm projectiles, said rear wall defining a perimeter; a front wall panel being mounted to said support framework structure and being disposed in spaced relation with said rear wall panel and defining a compartment therewith, said front wall being readily penetrable by the class of firearm projectiles and defining a perimeter; containment walls closing said perimeters of said rear and front wall panels and defining closures for said compartment; and a multiplicity of energy absorbing elements composed of hard and dense material and being arranged in loose and moveable relation within said compartment and being disposed in engagement with adjacent energy absorbing elements, said energy absorbing elements being contained by said front, rear and containment walls.
 12. The projectile energy absorbing and dissipating device of claim 11, comprising: said rear wall panel being composed of a hard and dense metal composition that is resistant to penetration by non-explosive firearm projectiles of the designated class; said front wall panel being composed of a material that is subject to penetration by the designated class of non-explosive firearm projectiles; and said multiplicity of energy absorbing elements being composed of a hard and dense metal material that is resistant to deformation by the designated class of non-explosive firearm projectiles.
 13. The projectile energy absorbing and dissipating device of claim 12, comprising: said multiplicity of energy absorbing elements being composed of hardened steel and being in the form of spheres
 14. The projectile energy absorbing and dissipating device of claim 12, comprising: said rear wall panel being composed of steel plate material having a thickness of from about ⅛″ to about ¾″; and said front wall panel being composed of a material that substantially closes the path of a projectile penetration and maintains the capability for containment of said energy absorbing elements after having been penetrated many hundreds of times by the designated class of non-explosive firearm projectiles.
 15. The projectile energy absorbing and dissipating device of claim 14, comprising: said front wall panel being composed of a polymer material having a long chain polymer structure providing an elastic memory for substantially closing projectile penetration paths after having been penetrated by the designated class of non-explosive projectiles.
 16. The projectile energy absorbing and dissipating device of claim 11 being in the form of a rotatably moveable bullet trap, and comprising: said support framework structure having an axis and being supported for rotation about said axis; and said containment walls having perforations of a dimension preventing movement of said multiplicity of energy absorbing elements therethrough and permitting movement of bullet fragment residue therethrough for deposit and collection.
 17. The projectile energy absorbing and dissipating device of claim 11 being in the form of a protective barrier for personnel and vehicles, and comprising: said rear wall being defined by rear wall panels of portable nature and being arranged to form an inner barrier wall structure and being moveable for re-use; said front wall being defined by front wall panels disposed in spaced relation with said rear wall panels and arranged to form an outer barrier wall structure and to define said compartment; said energy absorbing and dissipating elements being poured into said compartment and defining a mass of loose energy absorbing elements; and said multiplicity of projectile energy absorbing and dissipating elements being recoverable for re-use.
 18. A method for absorbing and dissipating the energy of projectile strikes by a class of non-explosive firearm projectiles up to 50 caliber, by shrapnel and by other fast moving objects, comprising: positioning front and rear walls in spaced relation defining an energy absorption and dissipation compartment therebetween, said front wall being readily penetrable by the projectiles and said rear wall being resistant to penetration by the projectiles; positioning a multiplicity of hardened energy absorbing elements of high mass within said energy absorption and dissipation compartment, said hardened energy absorbing elements of high mass being in contact with said front and rear walls; projectiles penetrating said front wall striking at least one of said hardened energy absorbing elements and imparting energy thereto; and transferring and dissipating the energy of a projectile strike through said multiplicity of hardened energy absorbing elements, causing disintegration of the projectile and providing penetration protection for said rear wall and for objects located beyond said rear wall.
 19. The method of claim 18, comprising: positioning said rear and front walls in portable fashion for movement and re-use; and recovering said multiplicity of hardened energy absorbing elements of high mass. 